LIGHT, (lymphotoxin-like, exhibits inducible expression and competes with HSV glycoprotein D for HVEM, a receptor expressed by T lymphocytes) is one potential cytokine target that has been implicated in the processes of chronic inflammatory autoimmune diseases (Mauri et al. 1998 Immunity 8 21-30). As a member of the TNF superfamily (TNFSF) of ligands, LIGHT is also known as TNFSF14 or CD258. LIGHT is expressed on the surface of T cells upon activation in a tightly regulated manner appearing within 4 hours, peaking by 12-24 hours and disappearing by 48 hours (Castellano et al. 2002 J Biol Chem 277 42841-51). However, LIGHT is also present at detectable levels constitutively on the surface of immature dendritic cells (Tamada et al. 2000 J Immunol 164 4105-10) and on T cells and natural killer (NK) cells of the gut (Cohavy et al. 2005 J Immunol 174 646-53). LIGHT mediates its biologic effects by binding three TNF superfamily receptors including the lymphotoxin β receptor (LTβR) (Crowe et al. 1994 Science 264 707-10, Browning et al. 1997 J Immunol 159 3288-98), the herpes virus entry mediator (HVEM) (Montgomery et al. 1996 Cell 87(3) 427-36), and decoy receptor 3 (DcR3) (Yu et al. 1999 J Biol Chem 274 13733-6).
Mice treated with an inhibitory LTβR-Fc fusion protein reduced the inflammatory symptoms in the CD4+CD45RBhigh T cell transfer model of colitis, a CD4+ T cell-mediated pathology (Mackay et al. 1998 Gastroenterology 115 1464-75). Constitutive transgenic T cell specific expression of LIGHT also has been shown to lead to severe intestinal inflammation with autoimmune-like pathology resembling human inflammatory bowel disease (IBD) (Wang et al. 2005 J Immunol 174 8173-82, Shaikh et al. 2001 J Immunol 167 6330-7, Wang et al. 2001 J Immunol 167 5099-105, Wang et al. 2004 J Clin Invest 113 826-35). LIGHT-expressing lymphocytes can induce IBD-like symptoms (e.g., cytokine profiles of human Crohn's disease, fissuring ulcers, ileitis, and increases in colonic IFN-γ and TNF) when mesenteric lymph node cells from LIGHT transgenic animals are transferred to RAG−/− (Wang et al. 2005 J Immunol 174 8173-82). In human disease, increases of LIGHT expression were observed in patients with active Crohn's disease (Cohavy et al. 2005 J Immunol 174 646-53, Wang et al. 2005 J Immunol 174 8173-82, Wang et al. 2004 J Clin Invest 113 826-35, Cohavy et al. 2004 J Immunol 173 251-8). LIGHT has also been demonstrated to be elevated in gut T cells of IBD patients (Cohavy et al. 2004 J Immunol 173 251-8). Genetic evidence also supports a role for LIGHT in IBD (Granger et al. 2001 J Immunol 167 5122-8); (Rioux et al. 2000 Am J Hum Genet 66 1863-70; Low et al. 2004 Inflamm Bowel Dis 10 173-81; Bonen and Cho 2003 Gastroenterology 124 521-36).
Moreover, CCL20-CCR6 signaling has been shown to be involved in IBD, and LIGHT induces CCL20 secretion from the human colonic epithelial cell line HT29.14s. In human studies, epithelial cells of the colon have been found to be a major source of CCL20 in IBD patients and CCL20 expression is increased in human IBD patients (Kwon et al. 2002 Gut 51 818-26; (Kaser et al. 2004 J Clin Immunol 24 74-85).
hLIGHT has also been implicated in graft-versus-host disease (GVHD). For example, LIGHT has been shown to provide potent costimulatory activity for T cells, enhancing proliferation an the production of Th1 cytokines independent of the B7-CD28 pathway (see, e.g., Tamada et al. 2000 J. Immunol. 164 4105-4110). Blocking of LIGHT-HVEM costimulation by either anti-HVEM monoclonal antibodies, HVEM-Ig, or LTβR fusion protein inhibits allogeneic T cell responses (see, e.g., Tamada et al. 2000 J. Immunol. 164 4105-4110, Harrop et al. 19998 J. Immunol. 161 1786). Furthermore, in vivo administration of LTβR-Ig or murine anti-LIGHT antibodies inhibits anti-host cytotoxic T lymphocyte (CTL) responses in a murine acute GVHD model (Tamada et al. 2000 Nat. Med. 6 283-289).
Although observations such as those discussed above indicate a role for LIGHT in inflammatory disorders, such as IBD or GVHD, to date no human anti-human LIGHT antibodies have been produced, nor have any human anti-hLIGHT antibodies or monoclonal anti-hLIGHT antibodies been shown to be antagonistic to hLIGHT biological activity. As such, a need continues to exist for identification of therapies, such as anti-LIGHT therapies, useful for treatment of inflammatory disorders in humans. Citation or discussion of a reference herein shall not be construed as an admission that such is prior art to the present invention.